Known truck/trailer boxes that are longitudinally straight and laterally curved, and which have a concave upper side and a convex lower side, are shown by the following United States Patents: U.S. Pat. No. 1,805,489, granted May 19, 1931, to Arthur G. Kerr and Daniel Merchant; U.S. Pat. No. 3,844,616, granted Oct. 29, 1974, to Douglas B. Acre; U.S. Pat. No. 4,948,155, granted Aug. 14, 1990, to Fred T. Smith and Fred P. Smith; U.S. Pat. No. 5,090,773, granted Feb. 25, 1992, to Bernard Guillsume; and U.S. Pat. No. 5,482,359, granted Jan. 9, 1996, to Albert A. Goodson. These patents should be carefully considered for the purpose of putting the present invention into proper prospective relative to the prior art.
There is a need for a way of constructing the sidewalls of the truck/trailer boxes from materials that are very lightweight but yet are strong and rigid. There is also a need for such a truck/trailer box construction that permits the sidewall to be built in sections that can be welded together while allowing for the use of very thin skins and webs that are themselves too thin to be welded. A principal object of the present invention is to fulfill these needs.